Dummy bar mechanism

ABSTRACT

A dummy bar mechanism for the continuous casting of metals in a mold sealingly connected with a casting vessel, comprising a starter head means destined to sealingly engage with said mold. The starter head means is equipped with a ventilation opening extending therethrough, and means are provided for preventing discharge of liquid metal through such ventilation opening.

United States Patent Evans 1 51 Apr. 4, 1972 [54] DUMMY BAR MECHANISM 211 Appl. No.: 54,700

FOREIGN PATENTS OR APPLICATIONS Saunders 164/274 UX 866,235 2/1953 Germany ..164/283 908,521 4/1954 1 Germany..... 810,062 8/1951 Germany 164/283 Primary Examiner-R. Spencer Annear Attorney-Parmeiee, Utzler & Welsh [30] Foreign Application Priority Data July 21, 1969 Sweden ..1 1 175/69 [571 ABSTRACT A dummy bar mechanism for the continuous casting of metals [52] [1.8. CI ..164/274, 164/82 in a mold li l n t d ith a asting vessel, comprising [51] Ill. CI ..B22d 11/08 a starter head means destined to li l engage i Said Fleld of Search 85, The starter head means is q pp a ventilation opening extending therethrough, and means are provided for [56] Reierences Cited preventing discharge of liquid metal through such ventilation UNlTED STATES PATENTS p 3,262,161 7/1966 Andrzejak et a] ..164/274 14 Claims, 6 Drawing Figures Patented April 4, 19 72 3,653,427

3 Sheets-Sheet 1 Fig.1

INVENTOR ATTORNEYS Patented A ril 4, 1972 3,653,427

3 Sheets-Sheet 2 INVENTOR CQQPQK M,

ATTORNEY! Patented April 4, 1972 SSheets-Sheet 5 nw z/v To? a 145 E 144 N5 DUMMY BAR MECHANISM BACKGROUND OF THE INVENTION The present invention broadly pertains to the continuous casting art, and, more specifically, has reference to an improved-dummy bar mechanism or arrangement for the continuous casting of metals.

One of the greatest difficulties encountered during continuous casting of metals in molds sealingly connected with the casting vessel, for instance during horizontal continuous casting, resides in the presence of the gas pressure which develops during casting in the hollow mold compartment. When the metal rushes into the mold compartment, the air entrapped therein suddenly heats up. The resultant expansion generates a pressure which can attain a value which is a multiple of the static pressure of the liquid melt. If water of condensation or a lubricant are located in the hollow compartment of the mold, then, due to evaporation or gasification, an actual explosion can occur. The rapid pressure increase prevailing in the hollow compartment of the mold is based upon the fact that the expanding air cannot escape at a sufficiently rapid rate from the hollow mold compartment. As a general rule, the starting head extending into the hollow mold compartment blocks the cross-section of the mold to such an extent that there only appears a relatively small gap. During escape of air or gas through this gap, liquid metal is entrained into the gap. In most instances, this results in an immediate binding of the dummy bar mechanism within the mold. If the mold is mounted so as to be movable, with a mouthpiece secured to the casting vessel engaging into the mold, then moreover, the danger exists that liquid melt or metal will also penetrate into the gap between the mouthpiece and the wall of the mold, thus binding the mold at the mouthpiece.

SUMMARY OF THE INVENTION Therefore, a real need exists in the art for a dummy bar mechanism which is not associated with the'aforementioned drawbacks of the prior art constructions. The present invention, therefore, has as one of its primary objectives to effectively fullfil this need and overcome the aforementioned disadvantages discussed in regard to the prior art systems.

Another, more specific object of the present invention relates to an improved dummy bar mechanism which effectively overcomes the disadvantages generated by virtue of the presence of gas pressure evolving during the casting of metal in the hollow mold compartment.

Still a further significant object of the present invention relates to improved dummy bar arrangement equipped with means for removal of the air existing in the hollow mold compartment at the start of the continuous casting operation so as to avoid the heretofore mentioned drawbacks which otherwise might occur as explained above.

Now, in order to implement these and still further objects of the present invention, which will become more readily apparent as the description proceeds, the inventive dummy bar mechanismfor the continuous casting of metals in a mold which is sealingly connected with a casting vessel, comprises a starter head which is destined to sealingly engage with the mold, this starter head being advantageously provided with a ventilation opening which extends throughthe starter head, and means are provided in order to prevent the discharge of liquid metal or melt through the ventilation opening.

By virtue of the provision of the ventilation opening or vent, as contemplated by the invention, and extending through the starter head, the gases expanding in the internal mold compartment during entry of the liquid melt are afforded the possibility of rapidly escaping, so that no excessive pressure can build up. On the other hand, the gas impervious sealing component prevents penetration of liquid melt into the gap between the starterhead and the inner wall of the mold, and therefore, avoids any blocking of the starter head in the mold. Furthermore, in or before the ventilation opening there are advantageously provided, according to the invention, certain measures which retain the liquid particles which are entrained by the gas stream in other words prevent their discharge together with the escaping gases. Although it is conceivable to utilize as such measures or expedients suitably arranged sheet metal members, for instance, a preferred manifestation of the invention contemplates the arrangement of a filter pack or filter means formed of steel wool or a metal grid in or before the ventilation opening, the metal droplets depositing at such filter means.

In certain instances, it can be advantageous to connect a pipe member at the ventilation opening, this pipe member extending into the hollow mold compartment and preferably terminating at the region of the mouthpiece of the casting vessel. If the opening of the pipe is located at a level which is attained by the liquid metal in the mold only shortly prior to the complete filling of the hollow mold compartment, then, the expanding gases can practically completely escape. As a result, air inclusions within the strand can accordingly be extensively prevented. When using a ventilation pipe or conduit the filter package or filter means is preferably arranged within the ventilation pipe, so that entrained metal droplets are entrapped within the pipe.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a cross-sectional view of a first embodiment of inventive dummy bar mechanism utilized in a vertically arranged mold of a continuous casting installation;

FIG. 2 is a cross-sectional view of a second embodiment of dummy bar mechanism for a horizontally arranged mold movable to and fro:

FIGS. 3 to 5 inclusive schematically depict front views of three respective variant forms of ventilation tubes or pipes; and

FIG. 6 is a further cross-sectional view of still another embodiment of dummy bar mechanism utilized in a horizontally arranged mold which is also movable to and fro.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, in' FIG. 1, there is depicted enough of a vertically arranged-continuous casting installation so that one versed in the art will readily understand the inventive concepts, particularly the novel aspects of the inventive dummy bar mechanism or arrangement. Turning now to FIG. 1 more specifically, it will be recognized that a casting vessel 2 is equipped with a vertically arranged mouth portion or mouthpiece 4. This casting vessel 2 communicates via a casting opening 6 extending through the mouthpiece 4 with the internal compartment 10 of a mold 8. Now, a dummy bar mechanism extends from the discharge end 12 of the mold into the hollow mold compartment 10, this dummy bar mechanismbeing generally designated by reference character 14. It will be seen to incorporate a strand secton l6 and a starter head 18 detachably secured to its front end. Moreover, starter head 18 will be seen to support at the side facing the hollow mold compartment 10 a sealing disk 20 which sealingly cooperates with the inner wall 10' of the mold 8. Sealing disk 20 can, for instance, be formed of asbestos or any other suitable high-temperature resistant material. Additionally, starter head 18 will be seen to support at its side facing the hollow mold compartment 10 a threadably attached starter bolt 22 as well as a ventilation pipe or vent pipe 24, which extends with its free open end 26 to the region of the mouthpiece or portion 4. The ventilation tube or pipe 24 which contains a filter insert 28 formed of steel wool, opens into a ventilation opening 30 which communicates with the surrounding atmosphere at the lower end of the starter head facing away from the hollow mold compartment 10.

If at the beginning of the casting operation liquid metal or melt, for instance steel, flows out of the casting vessel 2 via the casting opening 6 into the hollow mold compartment 10, thus expanding the air contained within the hollow mold compartment due to heating thereof, then, this expansion can occur without any appreciable pressure increase within the hollow mold compartment 10 since this air can escape into the atmosphere through the ventilation tube or pipe 24 and the ventilation opening 30. During such time as the hollow mold compartment l gradually fills with liquid metal and begins to solidify at the wall of the mold, air and any combustion gases which might tend to form can flow through the opening 26 into the ventilation pipe 24 and discharge therefrom, until the hollow mold compartment is approximately completely filled with liquid melt. Should metal spatters be entrained during the escape of the air and gases, as mentioned above, then such can deposit at the filter insert 28. When the liquid metal within the confines of the hollow mold compartment 10 has attained a level which is above that of the opening 26, then a portion of this liquid metal can also flow into the vent or ventilation tube 24. This liquid metal tends to rapidly cool within the relatively narrow cross-section of the ventilation tube 24 and solidifies within the filter insert 28. Consequently, the ventilation opening 30 automatically clogs at the end of the filling operation of the hollow mold compartment 10. Any gas which is still present within the hollow mold compartment cannot appreciably impair the casting operation, since this pressure practically corresponds to the static pressure of the metal.

It is to be observed that the end portion of the ventilation tube 24 defining the opening 26 is preferably bent towards the inner wall of the mold 8, so that the casting jet of metal entering the internal mold compartment 10 via the casting opening 6 cannot flow directly into the vent or ventilation tube 24.

Turning now to the embodiment of inventive dummy bar arrangement as depicted in FIG. 2, here it will be observed that the dummy bar mechanism 34 is arranged at a horizontally disposed mold unit 36 which communicates via a mouth portion or mouthpiece 38 with a casting vessel 40. The dummy bar mechanism 34, once again, possesses a starting or starter head 44 which is detachably connected with the dummy bar section 42. This starting head 44 furthermore is equipped with a sealing disk 48 at the side thereof facing the hollow mold compartment 46.

In contrast to the embodiment of FIG. 1, here the ventilation tube or pipe 50, threadably attached to the starting head 44, exercises a double function: the ventilation tube 50 simultaneously serves as a starter bolt member for anchoring the dummy bar at the metallic strand which is in the process of forming. To this end, in order to provide for a more rapid solidification of the strand material at the region of the ventilation tube 50, and therefore to achieve a better anchoring effect, the ventilation tube advantageously possesses ribs 52 or equivalent elements which extend in the peripheral direction of such ventilation tube, as shown. This ventilation tube or pipe 50 furthermore possesses a flexed free terminal piece 54, the mouth portion 56 of which confronts the inner wall of the mold 36. The end of the vent or ventilation tube 50 which is threaded into the starter head 44 communicates with the surrounding atmosphere via the ventilation channels 58 and 60.

During flow of liquid metal out of the casting vessel 40 into the hollow mold compartment 46 the latter fills up parallel to the lengthwise axis of the mold 36, the expanding air flowing away through the vent or ventilation tube 50. On the other hand, the sealing disk 48 prevents entry of liquid metal into the gap existing between the starter head 44 and the inner wall of the mold 36. Since the mouth or opening 56 of the ventilation tube 50 is located at a level which approximately corresponds to the level of the liquid metal when the hollow mold compartment 46 is completely filled, the expanding air or the air displaced by virtue of the mold filling operation can flow away almost to the termination of such filling operation. If the level of the liquid melt or metal has reached the opening 56, then the ventilation tube 50 is clogged by the inflowing liquid melt which tends to cool relatively rapidly, and before the liquid metal has reached the ventilation channels 58 and 60. If it is desired a filter insert can be provided at the ventilation pipe or tube 50 similar to the filter insert 28 utilized with the embodiment of FIG. 1.

Since the ventilation tube 50 simultaneously serves as a starter bolt member for the dummy bar, the starter head 44 can be removed from the ventilation tube 50 which has been cast with the starting portion of the strand, and after replacing the sealing disk 48 and inserting a new ventilation tube 50 can again be used.

Instead of utilizing the ventilation tube or pipe illustrated in conjunction with the embodiments of FIGS. 1 and 2, it would be equally possible to use the various constructions depicted in FIGS. 3, 4 and 5, respectively. The ventilation tube or pipe 62 depicted in FIG. 3 possesses two inlet connections 64 and 66 disposed at an angle to its lengthwise axis, with the inlet openings 68 and 70, respectively, being situation in a plane located parallel to the axis of such tube. Hence, with the ventilation tube 62 extending in a direction parallel to the axis of the mold, the inlet openings 68 and 70 thus confront the internal or inner wall of such mold.

In the arrangement of ventilation tube or pipe 72 as shown in FIG. 4 its free end 74 is closed or sealed-off. This ventilation tube 72 communicates with the associated hollow mold compartment through the agency of a plurality of bores or apertures 76 provided about its peripheral surface, as shown.

Turning now to the construction of ventilation tube or pipe 78 depicted in FIG. 5, especially suitable for use in a vertically arranged mold, such will be seen to encompass two inlet connections 80, the inlet openings 82 of which are situated in a plane disposed approximately perpendicular to the lengthwise axis of such tube. The free end 84 of the ventilation tube 78 is also here sealed or closed, to prevent entry of the casting jet into the confines of such tube.

The starter or starting head illustrated in FIG. G, and which if necessary may be rigidly connected with the dummy bar, is especially suitable for use with a horizontally arranged mold 38 of the type shown in FIG. 2. The mold may be displaceable along the casting vessel mouthpiece 38 or rigidly connected with the casting vessel. This starting head 90 will be seen to possess a cylindrical recess 92 at its end confronting the inner compartment of the mold. Cylindrical recess 92 merges with a conical portion 94 which, in turn, communicates with a ventilation opening or channel 96 or reduced cross-section. Ventilation opening 96 communicates via a bore 98 with the atmosphere prevailing externally of the mold 36. Further, arranged in front of the starter head 90 is a filter package or filter means 100 which is partially embeded in the cylindrical recess 92, whereas the portion of the filter means 100 located externally of the starter head 90 is enclosed by a suitable collar member 102 or equivalent structure. The portion of the filter means 100 which is located in the cylindrical recess 92 is pierced by a diametrically extending tubular element 104, through which extends a bolt 106 secured to the starter head 90. Tubular member 104 is engaged by a substantially V-shaped steel anchor 108, the leg portion of which is flexed at location 110 and extends into the hollow mold compartment 46, as shown.

Now, if during casting liquid metal flows through the mouthpiece 38 into the hollow mold compartment 46, then the expanding air contained in the hollow mold compartment escapes through the filter package or filtermeans 100, the conical portion 94, the channel 96 and the bore channel 98 externally of the mold. Depending upon the nature of the filling operation of the hollow mold compartment 46 liquid metal also flows into the filter package 100, but the liquid metal deposits at the intermediate spaces or voids of the filter package which, for instance, can be formed of steel wool. Hence, the deposit of such liquid melt in the hollow spaces of the filter package causes such to close and prevents the further through passage of liquid melt. On the other hand, the collar 102 prevents penetration of liquid metal into the gap between the starter head 90 and the inner wall of the mold 36. By using the collar 102, it is possible to obtain an exact fitting or accommodation of the starter head to the internal crosssection of the mold.

The embodiment of dummy bar arrangement or mechanism depicted in FIG. 6 has the advantage that venting of the internal mold compartment 46 can occur practically without increase of the internal pressure beyond the static pressure of the liquid metal, since there is provided a large surface connection via the filter package 100 to the ventilation channel 96 during each stage of filling of the hollow mold compartment. The starter head 90 can be easily reused: it is only necessary to remove the bolt 106, whereupon such can be withdrawn from the filter package. It is here also mentioned that with the various embodiments of inventive dummy bar arrangement, the filter package can be formed of suitable filter materials, such as steel wire, steel fabric or steel wool, by way of example.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. ACCORDINGLY.

I claim:

1. A continuous casting arrangement including a mold sealingly connected with a casting vessel, the improvement comprising a starter head capable of sealingly engaging with the mold, means providing a ventilation opening extending through said starter head, and means for preventing discharge of liquid melt through said ventilation opening.

2. A dummy bar mechanism as defined in claim 1, wherein said means for preventing discharge of liquid melt comprises filter means.

3. A dummy bar mechanism as defined in claim 2, wherein said filter means is formed of steel wool.

4. A dummy bar mechanism as defined in claim 2, wherein said filter means if formed of steel fabric.

5. A dummy bar mechanism as defined in claim 2, wherein said filter means is formed of steel wire.

6. A dummy bar mechanism as defined in claim 1, further including a ventilation tube extending from said ventilation opening into a hollow compartment of the mold.

7. A dummy bar mechanism as defined in claim 6, wherein said casting vessel is provided with a mouthpiece, and said ventilation tube possesses an inlet-opening which faces away from said casting vessel-mouthpiece.

8. A dummy bar mechanism as defined in claim 6, wherein said ventilation tube is constructed to provide a starting bolt means.

8. A dummy bar mechanism as defined in claim 6, wherein said means for preventing discharge of liquid metal comprises filter means, and said ventilation tube contains said filter means.

10. A dummy bar mechanism as defined in claim 6, wherein said ventilation tube is detachably secured to said starter head.

11. A dummy bar mechanism as defined in claim 1, wherein said starter head includes means for sealingly engaging with said mold which comprises a sealing disk member arranged at an end face of said starter head.

12. A dummy bar mechanism as defined in claim I, wherein said starter head includes means for sealingly engaging with said mold which comprises collar means arranged at an end face of said starter head.

13. A dummy bar mechanism as defined in claim 1, wherein said means for preventing discharge of liquid metal comprises filter means, said filter means being provided for said ventilation opening and being detachably secured with said starter head.

14. The mechanism as defined in claim 6, wherein the ventilation tube extends for substantially the entire length of the hollow compartment of the mold.

UNITED STATES PATENT oEETcE CERTIFIQATE 0F CORRECTWN Patent No. 3 ,653 ,427 Dated April 4, 1972 :[nventor( Clive Evans It is certified that error appears in the above-identified patent and that said Letters, Patent are hereby corrected as shown below:

Correct the cover sheet Item [30] Foreign Application Priority Data now incorrectly reads:

July 21, 1969 K Sweden 11175/69 should correctly read:

July 21, 1969 Switzerland 11175/69 Signed and sealed this 21st day of November 1972.

(SEAL) Attest:

EDWARD M.FLET JHER,JR. ROBERT GOTTSCHALK ttestlng Officer Commissioner of Patents FORM PO-1050 (\0-69) USCOMM-DC 603764 59 U.S, GOVERNMENT PRINTING OFFICE I969 O-356334 

1. A continuous casting arrangement including a mold sealingly connected with a casting vessel, the improvement comprising a starter head capable of sealingly engaging with the mold, means providing a ventilation opening extending through said starter head, and means for preventing discharge of liquid melt through said ventilation opening.
 2. A dummy bar mechanism as defined in claim 1, wherein said means for preventing discharge of liquid melt comprises filter means.
 3. A dummy bar mechanism as defined in claim 2, wherein said filter means is formed of steel wool.
 4. A dummy bar mechanism as defined in claim 2, wherein said filter means if formed of steel fabric.
 5. A dummy bar mechanism as defined in claim 2, wherein said filter means is formed of steel wire.
 6. A dummy bar mechanism as defined in claim 1, further including a ventilation tube extending from said ventilation opening into a hollow compartment of the mold.
 7. A dummy bar mechanism as defined in claim 6, wherein said casting vessel is provided with a mouthpiece, and said ventilation tube possesses an inlet openiNg which faces away from said casting vessel-mouthpiece.
 8. A dummy bar mechanism as defined in claim 6, wherein said ventilation tube is constructed to provide a starting bolt means.
 8. A dummy bar mechanism as defined in claim 6, wherein said means for preventing discharge of liquid metal comprises filter means, and said ventilation tube contains said filter means.
 10. A dummy bar mechanism as defined in claim 6, wherein said ventilation tube is detachably secured to said starter head.
 11. A dummy bar mechanism as defined in claim 1, wherein said starter head includes means for sealingly engaging with said mold which comprises a sealing disk member arranged at an end face of said starter head.
 12. A dummy bar mechanism as defined in claim 1, wherein said starter head includes means for sealingly engaging with said mold which comprises collar means arranged at an end face of said starter head.
 13. A dummy bar mechanism as defined in claim 1, wherein said means for preventing discharge of liquid metal comprises filter means, said filter means being provided for said ventilation opening and being detachably secured with said starter head.
 14. The mechanism as defined in claim 6, wherein the ventilation tube extends for substantially the entire length of the hollow compartment of the mold. 